How to test a capacitor with a multimeter

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How to test a capacitor with a multimeter

 A multimeter is an electrical measuring device with various functions. It can be used to check voltage, current, as well as derivatives of these values ​​- resistance and capacitance. Using a multimeter, you can also check the performance of various electronic components. In this article, we will learn how to check a capacitor and its capacitance with a multimeter.

Contents hide ]

  • 1 Capacitor and capacity
  • 2 Before checking the capacitor
  • 3 Measuring capacitance in resistance mode
    • 3.1 Models of multimeters on Aliexpress
  • 4 Measuring the capacitance of a capacitor
  • 5 Measuring capacitance through voltage
  • 6 Other verification methods
  • 7 Difficulties of verification
  • 8 How to Check Capacity - Youtube Videos

Capacitor and capacity

Capacitors are used in almost all microcircuits and are a common cause of its inoperability. So in the event of a device malfunction, this element should be checked first.

Types of capacitors by dielectric type:

  • vacuum;
  • with gaseous dielectric;
  • with inorganic dielectric;
  • with organic dielectric;
  • electrolytic;
  • solid state.
Electrolytic capacitors
Electrolytic capacitors are commonly used

The main malfunctions of capacitors:

  • Electrical breakdown. Usually caused by overvoltage.
  • Break. Associated with mechanical damage, shocks, vibrations. The reason may be a poor-quality design and violation of operating conditions.
  • Increased leakage. The resistance between the plates changes, and this leads to a low capacitance of the capacitor, which is not able to store a charge.

All these reasons lead to the fact that the capacitor becomes unusable for further use.

In this case, there is an electrolyte leak
In this case, there is an electrolyte leak

Before checking the capacitor

Because capacitors build up an electrical charge and must be discharged before testing. This can be done with a screwdriver - you need to touch the pins with a sting to create a spark. Then you can call the component. The capacitor test can be done both with a multitester and with the help of bulbs and wires. The first method is more reliable and gives more accurate information about the electronic item.

The condenser should be inspected prior to testing. If it is cracked, damaged, leaky or swollen, the internal electrolyte is damaged and the device is broken. It needs to be changed to a working device. In the absence of external damage, you will have to use a multimeter.

Before taking measurements, you need to determine the type of capacitor - polar or non-polar. The first must have the correct polarity, otherwise the device will fail. In the second case, the determination of the positive and negative outputs is not required, but the measurements will be carried out using a different technology.

You can determine the polarity by the mark on the case. The part should have a black stripe with a zero. There is a negative contact on the side of this leg, and a positive one on the opposite side.

Capacitance measurement in resistance mode

Measurement in resistance mode
Measurement in resistance mode

The multimeter switch should be set to resistance (ohmmeter) mode. In this mode, you can see if there is an open or short circuit inside the capacitor. To check a non-polar capacitor, a measurement range of 2 MΩ is set. For a polar product, a resistance of 200 ohms is set, since at 2 megohms, charging will be done quickly.

The capacitor itself must be unsoldered from the circuit and placed on the table. The probes of the multimeter need to touch the terminals of the capacitor, observing the polarity. In a non-polar part, it is not necessary to observe plus and minus.

Measurement in resistance mode
Measurement in resistance mode

When the probes touch the legs, the display will show a value that will increase. This is because the multitester will charge the component. After a while, the value on the screen will reach one, which means that the device is in good working order. If, during the check, 1 immediately lights up, an open circuit has occurred inside the device and should be replaced. A zero value on the display indicates that a short circuit has occurred inside the capacitor.

If a non-polar capacitor is tested, the value must be greater than 2. Otherwise, the device is not operational.

Analog device
Analog device

The above algorithm is suitable for a digital tester. When using an analog device, checking is even easier - you only need to observe the movement of the arrow. The probes are connected in the same way, the mode is resistance check. Smooth movement of the arrow indicates that the capacitor is working properly. The minimum and maximum values ​​when connected indicate a breakdown of the electronic part.

It is important to note that checking in ohmmeter mode is performed for parts with a capacitance above 0-1025 μF. For lower ratings, special LC meters or high resolution testers are used.

Measuring the capacitance of a capacitor

Capacity measurement
Capacity measurement

Capacitance is the main characteristic of a capacitor. It is indicated on the outer shell of the device, and if you have a tester, you can measure the real value and compare it with the nominal value.

The multimeter switch is transferred to the measurement range. The value is set equal to or close to the value indicated on the component. The capacitor itself is installed in special holes –CX + (if they are on the multimeter) or using probes. The probes are connected in the same way as when measuring in resistance mode.

When connecting the probes, the resistance value should appear on the monitor. If it is close to the nominal characteristic, the capacitor is good. When the discrepancy between the obtained and nominal values ​​differs by more than 20%, the device is punctured and needs to be replaced.

Measuring capacitance through voltage

Checking the performance of the part can also be performed using a voltmeter. The value on the monitor is compared with the nominal, and from this a conclusion is made about the health of the device. For testing, you need a power supply with a lower voltage than that of the capacitor.

Observing the polarity, you need to connect the probes to the terminals for a few seconds to charge. Then the multimeter is switched to the voltmeter mode and the operability is checked. The tester should display a value similar to the nominal value. Otherwise, the device is broken.

Other ways to check

You can check the capacitor without unsoldering it from the microcircuit. To do this, you need to connect in parallel a known good capacitor with the same capacity. If the device works, then the problem is in the first element, and it should be replaced. This method is only applicable in low voltage circuits!

Sometimes the capacitor is checked for a spark. It needs to be charged and with a metal tool with an insulated handle, close the leads. A bright spark with a characteristic sound should appear. With a small discharge, it can be concluded that it is time to change the part. This measurement must be carried out with rubber gloves. This method is used to test powerful capacitors, including starting ones, which are designed for a voltage of more than 200 volts.

It is undesirable to use test methods without special devices. They are unsafe - with the slightest carelessness, you can get an electric shock. The objectivity of the picture will also be violated - exact values ​​will not be obtained.

Difficulties of verification

The main difficulty in determining the performance of a capacitor with a multimeter is its desoldering from the circuit. If you leave the component on the board, the measurement will be affected by other circuit elements. They will distort the readings.

On sale there are special testers with reduced voltage on the probes, which allow you to check the capacitor directly on the board. Low voltage minimizes the risk of damage to other components in the circuit.

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